MBP 10.1 Big Sur bootlog reports many 'command not found'

Nothing blatantly obvious stands out but I strongly recommend ridding that Mac of the following nonessential software:

"Cocktail"

"Drive Genius"

"Spyhunter"

"TotalAV"

They convey no beneficial purpose. Uninstall both of those products in accordance with their respective instructions. Follow them to the letter, restart your Mac, and please write back if the problems continue. My next suggestion would be to run EtreCheck.

Something appears to be invoking a Terminal script upon logging in, and whatever that may be is probably being launched as either a system or user launch agent or daemon.

Start investigating by inspecting the contents of the following three folders:

~/Library/LaunchAgents

/Library/LaunchDaemons

/Library/LaunchAgents

All three.

If you need help doing that, read About those " will damage your computer" messages - Apple Community. It describes a different problem, but the means to investigate it remains the same, and it has illustrated step-by-step instructions. Post screenshots if you so choose — that document describes how to do that also.

It looks like something placed a utility called "BOOTLOG" on the normally hidden & unmounted "EFI" partition. I've never seen anything like this before. If this is the case, then deleting the "BOOTLOG" item would at least get rid of the errors shown in the Terminal app....perhaps with that gone it will reveal the app which is using it. The only folder within the normally hidden "EFI" on an Apple boot drive should be "apple" IIRC.

I'm definitely concerned about what & why an app would put any executable on there called "BOOTLOG", unless this is somehow just a very broken Zsh profile file. By default, macOS has no Zsh profile files in the home user folder (the Zsh profiles are hidden with several possible names), so renaming any such files located within your home user folder would be the quick way to possibly fix this issue although it is hard to say whether some other installed app/utility needed to customize a Zsh profile file.

Those are the two possibilities I can see. Personally I think it would be easier & better to perform a clean install of macOS by erasing the disk followed by installing macOS since this really seems weird....and I've seen a lot. You do not want to migrate from a backup as that will likely bring the problem back. You will just want to restore your data manually & download & reinstall only the third party apps you actually need. Don't install "junk" as @John Galt likes to say....there is no need for any anti-virus apps, cleaning/optimizer apps, or third party security software.

Of course posting a complete EtreCheck report as suggested by @John Galt may give us some clues for trying to fix & remove whatever caused this issue.

https://etrecheck.com

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

You still have all those third party apps installed that @John Galt suggested to uninstall. macOS does not need any third party anti-virus software. Even if it did, you never want to install more than one because they will step on each other's toes. macOS already has great built-in security especially when the user also practices safe computing habits as outlined in this excellent article compiled by our very own @John Galt, which I think should be read & practiced by everyone:

Effective defenses against malware and other threats - Apple Community

You also do not need any cleaning/optimizer apps, or third party security software. All of these types of apps (including AV) cause more problems than they solve because they interfere with the normal operation of macOS at a very low level.

You also have some very old outdated software still installed on this Mac that should be uninstalled.

I also see some odd boot arguments listed in the report....I have no idea what they do since I don't recall any other EtreCheck report ever showing any boot arguments. I am not familiar with any macOS boot arguments except for a few that may be used with the PRAM (aka NVRAM). A PRAM Reset may be appropriate in case the boot arguments are stored in the NVRAM, but it is possible some system level configuration file has been modified (I know nothing about that area).

You can try uninstalling at minimum the apps listed by @John Galt, and any of the other apps which fit the categories I listed here. You need to follow the developers' instructions for uninstalling their software & hope it removes all traces of it.....sometimes remnants may still remain. I'll leave it to @John Galt and others to advise you on any of the other third party apps & utilities since I am not a macOS software expert. Since there is so much going on here I would recommend a clean install and NO migration. Instead after the clean install, create a new macOS admin user account using Setup Assistant. Then just manually recover just your data files from the backup. Download & reinstall only the latest versions of the third party apps you actually need. In the end this would probably be the easiest & quickest way to end up with a clean reliable working system. At least this is what I would do if someone brought me this computer to fix.

Lance.scs wrote:

These are the volumes but the following order is completely different from my other Mac.

https://discussions.apple.com/content/attachment/512c5011-d4ad-45e7-b859-2a2fde489d1e

That looks fine. Unfortunately Apple keeps changing how the drive layout looks with every new OS. Underneath it hasn't really changed, but how Apple shows it to us keeps changing.

I was under the impression you uninstalled the nonessential software I described earlier, but each of the items I pointed out are still present and affecting that Mac to whatever extent they ever have. In other words that most recent report indicates you changed nothing, and no change in behavior can be expected.

A "clean install" is not defined by Apple so we are all left to interpret what that terminology means, but if that's what you did it doesn't square what I think it means.

There's no doubt that Mac is extensively modified. No judgement — the ability to modify a Mac is what distinguishes it from its iOS equivalents — but with each modification a user performs comes the responsibility for accepting whatever consequences may result. The requirement to constantly reevaluate the effect of macOS updates on those modifications and the responsibility to keep those modifications updated can easily become time-consuming, unproductive drudgery.

EtreCheck can often identify a definitive cause for any particular problem, but when it doesn't, it can reveal clues. In your case those clues amount to quite a few system modifications that convey no beneficial purpose, or what I broadly categorize as "junk". Of the system modifications present there are some that I am familiar with that should absolutely be removed (TotalAV to cite one of many), others that I am also familiar with that may be required for your needs (MS Office), leaving a large number of other obscure products I am not familiar with.

That last category is where I'd start looking because none of the products I'm familiar with (even the "junk") can account for the odd and apparently malformed script that is being invoked upon login. EtreCheck's "Minor Issues" is an excellent summation of the challenges you're facing.

Configuration Files:

/etc/hosts - Count: 212

There is something blatantly wrong about that. Again, no "smoking gun" but it's something you need to investigate. I recommend reading Mr. Etresoft's Fixing a hacked /etc/hosts file - Apple Community. Again — no judgement — but perhaps it will also reveal some clues.

You're welcome to post the contents of it here.

Limited permissions - More information may be available with Full Disk Access.

Please re-read How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community.

EtreCheck is an excellent time-saver when it comes to diagnosing someone else's Mac over this very limited communications medium. But in the end you might need to avail yourself of some hands-on, in-person evaluation. Otherwise erase the Mac completely and reconfigure it without the "junk". Unfortunately this tends to be the best advice we can come up with on this site, not only because it's guranteed to work, but it makes up for the inability to exhaustively examine each system modification and evey other potential cause. That's hard enough to do even with hands-on access.